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Diffstat (limited to 'kernel/sched_cpupri.c')
| -rw-r--r-- | kernel/sched_cpupri.c | 241 |
1 files changed, 0 insertions, 241 deletions
diff --git a/kernel/sched_cpupri.c b/kernel/sched_cpupri.c deleted file mode 100644 index a86cf9d9eb11..000000000000 --- a/kernel/sched_cpupri.c +++ /dev/null @@ -1,241 +0,0 @@ -/* - * kernel/sched_cpupri.c - * - * CPU priority management - * - * Copyright (C) 2007-2008 Novell - * - * Author: Gregory Haskins <ghaskins@novell.com> - * - * This code tracks the priority of each CPU so that global migration - * decisions are easy to calculate. Each CPU can be in a state as follows: - * - * (INVALID), IDLE, NORMAL, RT1, ... RT99 - * - * going from the lowest priority to the highest. CPUs in the INVALID state - * are not eligible for routing. The system maintains this state with - * a 2 dimensional bitmap (the first for priority class, the second for cpus - * in that class). Therefore a typical application without affinity - * restrictions can find a suitable CPU with O(1) complexity (e.g. two bit - * searches). For tasks with affinity restrictions, the algorithm has a - * worst case complexity of O(min(102, nr_domcpus)), though the scenario that - * yields the worst case search is fairly contrived. - * - * This program is free software; you can redistribute it and/or - * modify it under the terms of the GNU General Public License - * as published by the Free Software Foundation; version 2 - * of the License. - */ - -#include <linux/gfp.h> -#include "sched_cpupri.h" - -/* Convert between a 140 based task->prio, and our 102 based cpupri */ -static int convert_prio(int prio) -{ - int cpupri; - - if (prio == CPUPRI_INVALID) - cpupri = CPUPRI_INVALID; - else if (prio == MAX_PRIO) - cpupri = CPUPRI_IDLE; - else if (prio >= MAX_RT_PRIO) - cpupri = CPUPRI_NORMAL; - else - cpupri = MAX_RT_PRIO - prio + 1; - - return cpupri; -} - -/** - * cpupri_find - find the best (lowest-pri) CPU in the system - * @cp: The cpupri context - * @p: The task - * @lowest_mask: A mask to fill in with selected CPUs (or NULL) - * - * Note: This function returns the recommended CPUs as calculated during the - * current invocation. By the time the call returns, the CPUs may have in - * fact changed priorities any number of times. While not ideal, it is not - * an issue of correctness since the normal rebalancer logic will correct - * any discrepancies created by racing against the uncertainty of the current - * priority configuration. - * - * Returns: (int)bool - CPUs were found - */ -int cpupri_find(struct cpupri *cp, struct task_struct *p, - struct cpumask *lowest_mask) -{ - int idx = 0; - int task_pri = convert_prio(p->prio); - - if (task_pri >= MAX_RT_PRIO) - return 0; - - for (idx = 0; idx < task_pri; idx++) { - struct cpupri_vec *vec = &cp->pri_to_cpu[idx]; - int skip = 0; - - if (!atomic_read(&(vec)->count)) - skip = 1; - /* - * When looking at the vector, we need to read the counter, - * do a memory barrier, then read the mask. - * - * Note: This is still all racey, but we can deal with it. - * Ideally, we only want to look at masks that are set. - * - * If a mask is not set, then the only thing wrong is that we - * did a little more work than necessary. - * - * If we read a zero count but the mask is set, because of the - * memory barriers, that can only happen when the highest prio - * task for a run queue has left the run queue, in which case, - * it will be followed by a pull. If the task we are processing - * fails to find a proper place to go, that pull request will - * pull this task if the run queue is running at a lower - * priority. - */ - smp_rmb(); - - /* Need to do the rmb for every iteration */ - if (skip) - continue; - - if (cpumask_any_and(&p->cpus_allowed, vec->mask) >= nr_cpu_ids) - continue; - - if (lowest_mask) { - cpumask_and(lowest_mask, &p->cpus_allowed, vec->mask); - - /* - * We have to ensure that we have at least one bit - * still set in the array, since the map could have - * been concurrently emptied between the first and - * second reads of vec->mask. If we hit this - * condition, simply act as though we never hit this - * priority level and continue on. - */ - if (cpumask_any(lowest_mask) >= nr_cpu_ids) - continue; - } - - return 1; - } - - return 0; -} - -/** - * cpupri_set - update the cpu priority setting - * @cp: The cpupri context - * @cpu: The target cpu - * @pri: The priority (INVALID-RT99) to assign to this CPU - * - * Note: Assumes cpu_rq(cpu)->lock is locked - * - * Returns: (void) - */ -void cpupri_set(struct cpupri *cp, int cpu, int newpri) -{ - int *currpri = &cp->cpu_to_pri[cpu]; - int oldpri = *currpri; - int do_mb = 0; - - newpri = convert_prio(newpri); - - BUG_ON(newpri >= CPUPRI_NR_PRIORITIES); - - if (newpri == oldpri) - return; - - /* - * If the cpu was currently mapped to a different value, we - * need to map it to the new value then remove the old value. - * Note, we must add the new value first, otherwise we risk the - * cpu being missed by the priority loop in cpupri_find. - */ - if (likely(newpri != CPUPRI_INVALID)) { - struct cpupri_vec *vec = &cp->pri_to_cpu[newpri]; - - cpumask_set_cpu(cpu, vec->mask); - /* - * When adding a new vector, we update the mask first, - * do a write memory barrier, and then update the count, to - * make sure the vector is visible when count is set. - */ - smp_mb__before_atomic_inc(); - atomic_inc(&(vec)->count); - do_mb = 1; - } - if (likely(oldpri != CPUPRI_INVALID)) { - struct cpupri_vec *vec = &cp->pri_to_cpu[oldpri]; - - /* - * Because the order of modification of the vec->count - * is important, we must make sure that the update - * of the new prio is seen before we decrement the - * old prio. This makes sure that the loop sees - * one or the other when we raise the priority of - * the run queue. We don't care about when we lower the - * priority, as that will trigger an rt pull anyway. - * - * We only need to do a memory barrier if we updated - * the new priority vec. - */ - if (do_mb) - smp_mb__after_atomic_inc(); - - /* - * When removing from the vector, we decrement the counter first - * do a memory barrier and then clear the mask. - */ - atomic_dec(&(vec)->count); - smp_mb__after_atomic_inc(); - cpumask_clear_cpu(cpu, vec->mask); - } - - *currpri = newpri; -} - -/** - * cpupri_init - initialize the cpupri structure - * @cp: The cpupri context - * @bootmem: true if allocations need to use bootmem - * - * Returns: -ENOMEM if memory fails. - */ -int cpupri_init(struct cpupri *cp) -{ - int i; - - memset(cp, 0, sizeof(*cp)); - - for (i = 0; i < CPUPRI_NR_PRIORITIES; i++) { - struct cpupri_vec *vec = &cp->pri_to_cpu[i]; - - atomic_set(&vec->count, 0); - if (!zalloc_cpumask_var(&vec->mask, GFP_KERNEL)) - goto cleanup; - } - - for_each_possible_cpu(i) - cp->cpu_to_pri[i] = CPUPRI_INVALID; - return 0; - -cleanup: - for (i--; i >= 0; i--) - free_cpumask_var(cp->pri_to_cpu[i].mask); - return -ENOMEM; -} - -/** - * cpupri_cleanup - clean up the cpupri structure - * @cp: The cpupri context - */ -void cpupri_cleanup(struct cpupri *cp) -{ - int i; - - for (i = 0; i < CPUPRI_NR_PRIORITIES; i++) - free_cpumask_var(cp->pri_to_cpu[i].mask); -} |